/Engine/Source/Editor/Kismet/Public/BlueprintEditor.h
Called when a selection of nodes are being collapsed into a macro
[UEdGraph](API\Runtime\Engine\EdGraph\UEdGraph) * CollapseSelectionToMacro ( [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [SGraphEditor](API\Editor\UnrealEd\SGraphEditor) > InRootGraph, [TSet](API\Runtime\Core\Containers\TSet)< class [UEdGraphNode](API\Runtime\Engine\EdGraph\UEdGraphNode) * > & InCollapsableNodes, [UEdGraphNode](API\Runtime\Engine\EdGraph\UEdGraphNode) *& OutMacroNode )